Preparation of adhesive (CO) polymers from isocyanate chain extended narrow molecular weight distribution telechelic (CO) polymers made by pseudo living polymerization

ABSTRACT

Disclosed is a method for preparing adhesive polymers which commences with the formation of a poly-telechelic polymer of narrow molecular weight distribution (Mw/Mn) by polymerizing one or more radically-polymerizable monomers in the presence of a transition metal, a ligand, and an initiator, under atom or group transfer radical polymerization conditions. In this polymerization step, OH groups are contained on one or more of said initiator, an initiating monomer, a polymerizable monomer, a terminating monomer, or combinations thereof. The poly-telechelic polymer, then, is chain extended with a polyisocyanate to form the adhesive polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.08/965,548, filed Nov. 6, 1997, now U.S. Pat. No. 6,121,980 thedisclosure of which is expressly incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to the synthesis of adhesive compositionsand more particularly to the synthesis of telechelic polymers ofselected narrow molecular weight distribution for use in adhesives,coatings, and like applications. For present purposes, “telechelic”polymers are polymers that contain reactive end groups. “Polytelechelic”(co)polymers, then, contain two or more reactive pendant groups whichoften are end groups. For present purposes, “polymers” includehomopolymers and copolymers (unless the specific context indicatesotherwise), which may be block, random, gradient, star, graft (or“comb”), hyperbranched, or dendritic. The “(co)” parenthetical prefix inconventional terminology is an alternative, viz., “(co)polymer” means acopolymer or polymer, which includes a homopolymer.

Conventional free radical polymerization leads to synthesis of polymerswith a fairly broad molecular weight distribution, Mw/Mn (weightmolecular weight/number molecular weight), or polydispersity, in therange of 2.5 to 3. Number molecular weight (Mn) relies on the number ofmolecules in the polymer, while weight molecular weight relies on theweight of the individual molecules. See, e.g., Solomon, The Chemistry ofOrganic Film Formers, pp. 25, et seq., Robert E. Krieger Publishing Co.,Inc., Huntington, N.Y. (1977), the disclosure of which is expresslyincorporated herein by reference. The basic theory that applies to thecontrol of the growth of the polymer chains and Mw/Mn ratios in afree-radical initiated polymerization reaction is well documented in theliterature by P. J. Flory, JACS, Vol. 96, page 2718 (1952).

State of the art practice used to prepare polymers with a narrowmolecular weight distribution in the range of, say, 1.05 to 1.4, rely onliving polymerization techniques, such as anionic and cationicpolymerization. These ionic living polymerization techniques haveseveral limitations including, for example, restrictions on the types ofmonomers that can be polymerized, low temperature and purity processrequirements, the inability to synthesize high molecular weightpolymers, etc. Because of these constraints, ionic polymerizationprocesses are limited to the synthesis of polymers based on styrene,isoprene, isobutylene, and like monomers to produce synthetic elastomersand thermoplastic rubbers.

Telechelic polymers prepared from either living polymers or condensationpolymers, such as polyesters, for example, tend to be of low molecularweight, typically on the order of several hundreds to several thousands(e.g., 500-10,000). This low molecular weight limitation makesconventional telechelic polymers impractical for a variety ofapplications including, for example, adhesives.

Recent work on atom transfer radical polymerization (ATRP) has shown thepotential of using this pseudo-living polymerization technique toprepare high molecular weight polymers based on acrylic monomers, vinylmonomers, and other common monomers which polymers exhibit a fairlynarrow molecular weight distribution, say, in the range of 1.05 to 1.5.Molecular weights up to 10⁵ have been claimed to have been synthesizedby ATRP techniques. See Patten, et al., “Radical Polymerization YieldingPolymers with Mw/Mn ˜1.05 by Homogeneous Atom Transfer RadicalPolymerization”, Polymer Preprints, pp. 575-576, No. 37 (March 1996);Wang, et al., “Controlled/”Living” Radical Polymerization. Halogen AtomTransfer Radical Polymerization Promoted by a Cu(I)/Cu(II) RedoxProcess”, Macromolecules 1995, 28, 7901-7910 (Oct. 15, 1995); andPCT/US96/03302, International Publication No. WO 96/30421, publishedOct. 3, 1996, the disclosures of which are expressly incorporated hereinby reference.

BRIEF SUMMARY OF THE INVENTION

Disclosed is a method for preparing adhesive polymers which commenceswith the formation of a poly-telechelic polymer of narrow molecularweight distribution (Mw/Mn), say from about 1-3, by polymerizing one ormore radically-polymerizable monomers in the presence of a transitionmetal, a ligand, and an initiator, under atom or group transfer radicalpolymerization conditions. In this polymerization step, OH groups arecontained on one or more of said initiator, an initiating monomer, apolymerizable monomer, a terminating monomer, or combinations thereof,that is, (i) one or more of the initiator, an initiating monomer, ahydroxy monomer, or combinations thereof; on (ii) one or more of ahydroxy monomer, a terminating monomer, or combinations thereof; or on(iii) one or more of the initiator, an initiating monomer, orterminating monomer, or combinations thereof. The poly-telechelicpolymer, then, is chain extended with a chain extension agent, such as apolyisocyanate, to form the adhesive polymer.

Regression analysis reveals that the adhesive properties of the chainextended polymers is dependent primarily upon the Mn of the telechelicpolymer and the hydroxyl monomer and/or initiator used in forming thetelechelic polymers. Data demonstrating such adhesive properties is setforth herein.

DETAILED DESCRIPTION OF THE INVENTION

In the polytelechelic polymer formation step of the process, atom orgroup transfer radical polymerization conditions are used. Suchconditions can be found described in, for example, the art cited aboveand incorporated herein be reference. Included in this step are atransition metal, a ligand, and an initiator.

Preferred transition metals are Cu⁺¹, and Co⁺¹, although many othertransition metals have been disclosed in the art and may find advantagein the present invention. Cu⁺¹ halides, for example, arc described withrespect to catalyzed reactions of organic polyhalides with vinylunsaturated compounds are well known by Bellus, Pure and AppliedChemistry, Vol. 57, No. 12, pp. 1827-1838 (1985). Complexing oftransition metal halides with organic ligands as part of the initiatorsystem is described in U.S. Pat. No. 4,446,246, for example. Cu⁺¹halide-bipyridine complexes with active organic halide compounds aredescribed to react with vinyl unsaturated compounds by Udding, et al.,J. Organic Chemistry, Vol. 59, pp. 1993-2003 (1994). Organocobaltporphyrin complexes (alkyl cobaloximes) are described in thepolymerization of acrylates by Wayland, et al., JACS, Vol. 116, pp.7943-7966 (1994). Cu⁺¹ carboxylate complexes formed from thiophenecarboxylates are described by Weij, et al., Polymer Preprints, Vol. 38,No. 1, pp. 685-686 (April 1997). The disclosures of the foregoingreferences are expressly incorporated herein by reference.

The generation of radical intermediates by reacting some transitionmetal species, including salts and/or complexes of Cu, Ru, Fe, Va, Nb,and others, with alkyl halides, R-X, is well documented (see Bellus,Pure & Appl. Chem., 1985, 57, 1827; Nagashima, et al., J. Org. Chem.,1993, 58, 464; Seijas, et al., Tetrahedron, 1992, 48(9), 1637;Nagashima, et al., J. Org. Chem., 1992, 57, 1682; Hayes, J. Am. Chem.Soc., 1988, 110, 5533; Hirao, et al., Syn. Lett., 1990, 217; Hirao, etal., J. Synth. Org. Chem., (Japan), 1994, 52(3), 197; Iqbal, et al.,Chem. Rev., 94, 519 (1994); Kochi, Organometallic Mechanisms andCatalysis, Academic Press, New York, 1978. Moreover, it also is knownthat R-X/transition metal species-based redox initiators, such asMo(CO)₆/CHCl₃, Cr(CO)₆/CCL₄, Co₄(CO)₁₂/CCl₄, and Ni[P(OPh))₃]₄/CCl₄,promote radical polymerization (see Bamford, Comprehensive PolymerScience, Allen, et al., editors, Pergamon: Oxford, 1991, vol. 3, p.123). The participation of free radicals in these redoxinitiator-promoted polymerizations was supported by end-group analysisand direct observation of radicals by ESR spectroscopy (see Bamford,Proc. Roy. Soc., 1972, A, 326, 431). The disclosures of the foregoingreferences are expressly incorporated herein by reference.

Ligands useful in the polytelechelic polymer formation step of theprocess also have been disclosed in the literature, such as set forthabove. Such ligands most readily are halides; although, bipyridyls,mercaptides, triflates (CuOSO₂CF₃ , J. Am. Chem. Soc., 95, 1889 (1973),incorporated herein by reference), olefin and hydroxyl complexes (see,Cotton and Wilkinson, Advanced Inorganic Chemistry, 3^(rd) Ed. Chapter23, John Wile & Sons, New York, N.Y. (1972; “Inorganic andOrganometallic Photochemistry”, M. S. Wrighton, Editor, ACS-Advances inChemistry Series, 168 (1978); and Srinivasan, J. Am. Chem. Soc., 85,3048 (1963), incorporated herein by reference) can be used as necessary,desirable, or convenient. The disclosures of the foregoing referencesare expressly incorporated herein by reference.

Initiators also have been disclosed in the literature. Representative ofsuch initiators include, for example, 2-hydroxyethyl 2-bromopropionate,2-hydroxyethyl 4-bromopropionate, methyl 2-bromopropionate, 1-phenylethyl chloride, 1-phenylethyl bromide, chloroform, carbon tetrachloride,2-chloropropionitrile, lower alkyl (C₁-C₆) esters of 2-halo-lower alkylcarboxylic acids (e.g., ethyl 2-bromoisobutyrate), α, α′-dichloroxylene,α, α′-dibromoxylene, hexakis(α-bromomethyl)benzene, and like. Obviously,halide initiators have been taught by the art to be preferred and suchinitiators serve quite efficaciously in the present invention. It shouldbe observed, further, that photoinitiators also can be used, such astaught by M. P. Greuel, “Living Free-Radical Polymerization Using AlkylCobaloximes as Photoinitiators”, Doctoral Thesis, University of Akron,December 1992. The disclosures of the foregoing references are expresslyincorporated herein by reference.

Referring now to radically-polymerizable monomers, broadly, suchmonomers include any ethylenically unsaturated monomer or oligomer whichcan be (co)polymerized in the presence of a the initiator. In adhesivestechnology, acrylic or acrylate compounds find wide acceptance inindustry. Another suitable class of ethylenically unsaturated compoundsare vinyl compounds, while a third broad class are compounds containingbackbone ethylenic unsaturation as typified by ethylenically unsaturatedpolyester oligomers. For terminating or capping the polymer ends with OHfunctionality, monomers modified to contain such functionality are usedin the polymerization step of the present invention.

Referring with more particularity to reactive acrylic or acrylatemonomers or oligomers, a variety of monoacrylate monomers find use inaccordance with the present invention. Monoacrylates include, forexample, allyl (meth)acrylate, C₁-C₂₂ alkyl and cycloalkyl(meth)acrylates, such as, for example, butyl acrylate, 2-ethylhexylacrylate, isooctylacrylate, amyl acrylate, lauryl acrylate, iso-propylacrylate, and the like, and corresponding monomethacrylates whichinclude, for example, benzyl methacrylate, stearyl methacrylate, decylmethacrylate, cyclohexyl methacrylate, and the like, and mixturesthereof. The foregoing monomers are merely representative and notlimitative of the list of acrylate and methacrylate monomers suitablefor use in the present invention as those skilled in the art willappreciate.

Other suitable reactive compounds for use in the present inventioninclude, for example, acrylated epoxy resins, acrylated silicone resins,acrylated polyurethane resins, and the like and mixtures thereof. Suchacrylate-functional compounds are well known in the art and little moreabout them need be stated here.

Hydroxyl-containing acrylic monomers include hydroxyl derivatives ofthose monomers named above (e.g., hydroxy ethyl acrylate or hydroxyethyl methacrylate), and the like, and mixtures thereof.

Hydroxy-functional initiators can be used in order to cap one end of thepolymer (i.e., initiate the polymer). Alternatively, a pre-monomer canbe used to start the polymerization which then proceeds withnon-functional monomers. The other end of the polymer can be terminatedwith such functionality by choice of monomer which can be functional ora functional monomer (for example, allyl alcohol) can bepost-polymerization added to cap the polymer with desired hydroxylfunctionality. In this regard, it will be appreciated that theefficiency of hydroxyl incorporation into the telechelic (co)polymers ismuch greater when a hydroxy initiator or hydroxy initial monomer isused, rather than end-capping with a functional monomer, as thoseskilled in the art will appreciate. Mono and di-hydroxyl functionaltelechelic (co)polymers are preferred for use in the present invention;although, high functionality may be useful on occasion as is necessary,desirable, or convenient.

Polyisocyanates, preferably diisocyanates, are conventional in natureand include, for example, hexamethylene diisocyanate, toluenediisocyanate (TDI), diphenylmethane diisocyanate (MDI), m- andp-phenylene diisocyanates, bitolylene diisocyanate, cyclohexanediisocyanate (CHDI), bis-(isocyanatomethyl) cyclohexane (H₆XDI),dicyclohexylmethane diisocyanate (H₁₂MDI), dimer acid diisocyanate(DDI), trimethyl hexamethylene diisocyanate, lysine diisocyanate and itsmethyl ester, isophorone diisocyanate, methyl cyclohexane diisocyanate,1,5-napthalene diisocyanate, xylylene and xylene diisocyanate and methylderivatives thereof, polymethylene polyphenyl isocyanates,chlorophenylene-2,4-diisocyanate, and the like and mixtures thereof.Triisocyanates and high-functional isocyanates also are well known andcan be used to advantage; although, diisocyanates are presentlypreferred. Aromatic and aliphatic diisocyanates, for example, (includingbiuret and isocyanurate derivatives) often are available as pre-formedcommercial packages and can be used to advantage in the presentinvention. As with conventional urethane reactions, there should be aslight to moderate excess of isocyanate equivalents compared to thehydroxyl equivalents of the telechelic (co)polymers being chainextended.

The chain extended poly-telechelic polymers find wide use in formulatingadhesives. Such adhesive polymers retain bond strength by dint of theirhigher molecular weight, but also exhibit good peel properties as dolower molecular weight polymers while still maintaining desiredviscosities of prior art adhesives. Thus, the chain extended adhesivepolymers exhibit a combination of bond strength which is expected ofhigh molecular weight polymers, while also exhibiting peel propertiesexpected of much lower molecular weight polymers. Such peel propertiesand good viscosities are believed to result because of the narrowmolecular weight distribution of the poly-telechelic polymerintermediates synthesized in accordance with the precepts of the presentinvention.

The compounding of the inventive adhesive polymers into useful adhesiveformulations follows conventional processing and handling which are wellknown to the skilled artisan. In this application, all units are in themetric system unless otherwise expressly indicated. Also, all citationsare expressly incorporated herein by reference.

EXAMPLES GENERAL PROCEDURES

Raw Materials

Butyl acrylate (BA), 4-hydroxybutyl acrylate (HBA), methyl2-bromopropionate (2-MPN), 1-bromoethyl benzene (1-BEB), allylalcohol(AllylOH), 5-hydroxypentene (Pentene-OH), copper bromide (CuBr), andbipyridine were obtained from Aldrich Chemicals and used without furtherpurification. 2-bromopropionic acid and anhydrous ethyleneglycol alsowere purchased from Aldrich Chemicals.

Hydroxy-Containing Initiator Synthesis Methods

2-Hvdroxyethyl 2-Bromopropionate (2-H2PN)

Dicyclohexylcarbodimide (4.1 g, 20 mmol), anhydrous ethylene glycol (5.0g, 81 mmol), and pyridine (1 ml, 12 mmol) were charged into a vial.Acetone (14 ml) and 2-bromopropionic acid (1.5 ml, 16.7 mmol) were addedwhile cooling the vial down with an ice bath to control the exothermicreaction. After stirring the vial's contents overnight, undissolvedby-products were removed by filtration. To the filtered reaction mixturewere added AcOEt (20 ml) and saturated NaCl water (15 ml) followed byshaking well. The reaction mixture separated into 2 layers. The upperAcOEt layer was washed with dilute HCI once and saturated NaCl water (15ml) two more times and then dried with MgSO₄. After removing MgSO₄,AcOEt was rotary evaporated to obtain a crude product. This crudeproduct was purified by silica gel chromatography (eluent:AcOEt:hexane=1:1 by weight) to yield 1.4 g (43% yield) product.

2-Hydroxyethyl 4-Bromopropionate (2-H4PN)

The foregoing procedure was repeated using 1,4-butanediol as thestarting material and anhydrous ethyleneglycol.

EXAMPLES 1-12 Typical Polymerization Method

Table 1, Examples 1-12

2-MPN, HBA (Example 2)

BA (12.8 g, 100 mmol) was charged into a four-neck flask equipped with amechanical stirrer, N₂ inlet, cooling condenser, and rubber septum.Bipyridine (400 mg, 2.56 mmol) and Cu(I)Br (123 mg, 0.86 mmol) wereadded to the flask. The flask was purged with N₂ for at least 1 hourafter which 2-MPN initiator (96 μl, 0.86 mmol) was injected into theflask through the rubber septum at ambient temperature. The reactionmixture then was stirred while being heated up to 110°-120° C. for 6hours.

After verifying that the conversion ratio (dried polymer weight/neatreaction polymer weight) exceeded 95%, HBA (130 μl, 0.94 mmol) was bulkadded through the rubber septum at 110°-120° C. The reaction solutionthen was heated for another 3 hours after which heating ceased. Thecrude polymer was diluted with ethyl acetate (50 ml) and then washedwith diluted aqueous HCl three times and saturated aqueous NaCl threetimes followed by drying with anhydrous MgSO₄. After filtering out MgSO₄and removing ethyl acetate, the polymer residue was dried by a vacuumpump at 50° C. overnight.

2-H2PN, Pentene-OH (Example 12)

BA (25.6 g, 200 mmol) was charged into a four-neck flask equipped with amechanical stirrer, N₂ inlet, cooling condenser, and rubber septum.Bipyridine (840 mg, 5.38 mmol) and Cu(I) Br (257 mg, 1.79 mmol) wereadded to the flask. The flask was purged with N₂ for at least 1 hourafter which the bromo initiator, 2-H2PN (400 mg, 1.79 mol), was injectedinto the flask through the rubber septum at ambient temperature. Thereaction mixture then was stirred for 6 hours while being heated up to110°-120° C.

After verifying that the conversion ratio (dried polymer weight/neatreaction polymer weight) exceeded 95%, penteneOH (1.54 g, 17.9 mmol) wasbulk added through the rubber septum at 110°-120° C. The reactionsolution then was heated overnight after which heating ceased. The crudepolymer was diluted with ethyl acetate (50 ml) and then washed withdiluted aqueous HCl three times and saturated aqueous NaCl three timesfollowed by drying with anhydrous MgSO₄. After filtering out MgSO₄ andremoving ethyl acetate, the polymer residue was dried overnight by avacuum pump at 50° C.

TABLE 1 Hydroxy-Containing Polymers OH Mn Example No. Monomer Initiator*Comonomer Terminator (calculated) Mw Mw/Mn 1 BA 2-MPN — — 43,567 69,7011.60 (B-4-1)  (12.8 g, (0.27 mmol) (47,650) Comparative 100 mmol) 2 BA2-MPN HBA — 15,538 34,491 2.22 (B-8-2)  (12.8 g, (0.90 mmol) (0.94 mmol)(14,450 100 mmol) 3 BA 1-BEB HBA — 16,170 30,319 1.88 (B-19-1) (12.8 g,(0.88 Mmol) (0.94 mmol) (14,580) 100 mmol) 4 BA 1-BEB HBA — 16,04133,274 2.08 (B-24-1) (25.6 g, (1.79 mmol) (2.67 mol)  (14,580) 200 mmol)5 BA 2-MPN — AllylOH 14,677 28,399 1.94 (B-13-1) (12.7 g,  (0.9 mmol)(1.47 mmol) (14,400) 100 mmol) 6 BA 1-BEB — AllylOH 15,209 26,923 1.77(B-48-1) (25.6 g, (1.76 mmol) (excess) (14,600) 200 mmol) 7 BA 2-H2PN —— 13,255 31,482 3.02 (B-39-1) (12.8 g,  (0.9 mmol) (14,500) 100 mmol) 8BA 2-H4PN — — 12,850 31,193 2.43 (B-45-1) (12.8 g, (0.89 mmol) (14,600)100 mmol) 9 BA 2-H4PN HBA — 15,103 26,861 1.78 (B-49-1) (12.8 g, (0.89mmol) (0.91 mmol) (14,800) 100 mmol) 10  BA 2-H4PN — AllylOH 14,95633,234 2.22 (B-46-1) (25.6 g, (1.78 mmol) (29.4 mmol) (14,700) 200 mmol)11  BA 2-H2PN — AllylOH 84,926 214,519  2.53 (B-52-1) (12.8 g,  (1.0mmol)  (110 mmol) (126,000)  100 mmol) 12  BA 2-H2PN — PenteneOH 21,89734,889 1.60 (B-56-1) (25.6 g,  (200 mmol) (17.9 mmol) (14,600) 200 mmol)*Ratio of Initiator/CuBr/Bipyridine was fixed at 1 mol eq/1 mol eq/3 moleq.

Example 1 synthesis is a control run in that neither the initiator norany monomer contained hydroxy functionality, nor was the polymerterminated with a hydroxy terminating monomer. The polymers synthesizedin Examples 2-4 both were synthesized using hydroxy functionalco-monomers; although, the initiator did not contain hydroxyfunctionality. The polymers synthesized in Examples 5-6 were bothinitiated with non-hydroxy functional initiators and neither containedany hydroxy functional co-monomers; although, each was polymer wasterminated with allyl alcohol. The polymers synthesized in Examples 7-8were initiated with a hydroxy functional initiator, although, none ofthe monomers contained hydroxy functionality. The polymers synthesizedin Examples 9-10 both were initiated with hydroxy functional monomers.In Example 9, however, a hydroxy functional co-monomer was used and inExample 10, the polymer was terminated with allyl alcohol. Finally, thepolymers synthesized in Examples 11-12 were both initiated with ahydroxy functional initiator and terminated with either allyl alcohol(Example 11) or with pentene alcohol (Example 12).

EXAMPLES 13-24 Typical Chain Extension Procedure

Table 2. Examples 13-24

Example 14 (below)

The polymer synthesized in Example 2 (Mn=15, 538, 1.35 g, 0.087 mol,0.092 mmol OH equivalents) was charged into a reaction vial and dilutedwith tetrahydrofuran (THF) (1.6 ml). Added thereto were 1 wt-%dibutyltin dilaurate (DBTL) in THF (120 mg, 1.9 μmol) and 10 wt-%4,4′-methylenebis(phenyl isocyanate) (120 mg, 0.048 mmol, 0.096 mmol NCOequivalents, NCO/OH ratio in reaction mixture of 1.0) followed bystirring for 2 hours under heating at 60° C. The molecular weight of theresulting product was determined by gel permeation chromatography usingpolystyrene as the standard.

Following the general procedures detailed above, the polymerssynthesized as reported in Table 1 were chain extended with4,4′-methylenebis(phenyl isocyanate) to produce polymers which haveutility in formulation adhesive compositions. The chain extensionresults are reported in Table 2, below

TABLE 2 Chain Extension by Reaction of Polymers of Table 1 (Examples1-12) with Diisocyanates Chain Extension Table 1 Table 1 Data NCO/OHChain Extension Data Ex. No. Ex. No. Mn Mw Mw/Mn (eq) Mn Mw Mw/Mn 13 143,567 69,701 1.60 — — — No Reaction 14 2 15,538 34,491 2.22 1.0 25,03650,558 2.02 15 3 16,170 30,319 1.88 1.2 22,983 108,529  4.72 16 4 16,04133,274 2.08 1.2 23,761 287,627  12.11 17 5 14,677 28,399 1.94 1.2 15,86535,338 2.23 18 6 15,209 26,923 1.77 1.4 18,523 33,706 1.82 19 7 13,25531,482 3.02 1.4 18,274 55,090 3.02 20 8 12,850 31,193 2.43 1.2 16,60757,084 3.44 21 9 15,103 26,861 1.78 2.0 46,587 259,875  5.18 22 10 14,956 33,234 2.22 1.5 27,148 73,219 2.70 23 11  84,926 214,519  2.531.4 106,001  334,315  3.15 24 12  21,897 34,889 1.60 1.8 48,438 252,259 5.22

The results reported in Table 2 indicate that a variety ofhydroxy-containing polymers can be produced that have Mw/Mn valuesranging between about 1.6 and 3.0. These results further demonstratethat chain extension of the hydroxy-containing polymers in Table 1produces new polymers that have Mw/Mn values that range between 1.82 and12.11. Although, the Mw/Mn values of the chain extended polymers do notexhibit the narrowness in number that their corresponding hydroxyfunctional telechelic (co)polymers from they are derived do, such chainextended (co)polymers indeed display very unusual adhesive properties asdata presented below will demonstrate. Polymers that do not containhydroxyl functionality (Example 1 in Table 1 and Example 29 in Table 2)do not react with the diisocyanate chain extenders.

EXAMPLE 25

Finally, the non-chain extended polymers synthesized in Examples 11 and12 (Table 1), and the chain extended versions (same MDI isocyanate as inthe previous examples) thereof synthesized in Examples 23 and 24 (Table2), were tested for their adhesive qualities by measuring their tack bythe Polyken Tack Test (see, for example, U.S. Pat. No. 4,183,834 fortest details, the disclosure of which is expressly incorporated hereinby reference). Additionally, two conventional polymers (identified asReference 1 and Reference 2) were synthesized from the same ingredientsas used in Examples 11 and 12, except that they were conventionallysynthesized by free-radical addition polymerization. The resultsrecorded are set forth in Table 3, below.

TABLE 3 Tack Test No. Mn Mw Mw/Mn (grams/cm²) 1-Example 11 84,926214,519 2.53 261 1-Example 23 106,001  334,315 3.15 128 2-Example 1221,897  34,889 1.60 320 2-Example 24 48,438 252,259 5.22 284 Reference 122,732  57,467 2.53 142 Reference 2 122,157  320,608 2.62  55

These results demonstrate that the inventive polymers have good tackwhen synthesized, as expected. When they are chain-extended with anisocyanate, tack decreases, as expected; however, increased molecularweight conventionally translates into stronger bonds. Unexpectedly, itwill be observed that the inventive isocyanate-extended telechelicpolymers retained a much higher adhesive strength at the highermolecular weights. This is unexpected. For example, compare the tackresults for Test No. 1—Example No. 23 and Reference 2. These polymershave about the same molecular weight; yet, the inventive polymerdisplays a tack of 128 g while the comparative polymer displays a tackof only 55 g. Moreover, the peel strength of the inventiveisocyanate-extended telechelic polymers can be tailored by judiciousselection of monomer ingredients and degree of reaction.

Thus, the inventive isocyanate-extended telechelic polymers can besynthesized to higher molecular weights to retain their strength by dintof the increased molecular weight, while also retaining a much high peelstrength that heretofore would be expected of much lower molecularweight polymers. Truly, an unusual blend of performance characteristicsare demonstrated by these data.

EXAMPLES 26-32

Additional hydroxy-functional block copolymers and their chain extendedderivatives were synthesized by the procedures described above, asfollows:

TABLE 4 Example Monomers* Initiator Terminator Mn Mw Mw/Mn 26 BA/MMA/BA2-H2PN Allyl OH 23,000 44,000 1.9 (1.8 mmol) (110 mmol) 27 BA/STY/BA2-H2PN Pentene OH 23,000 50,000 2.19 (1.8 mmol) (210 mmol) *STY isstyrene

TABLE 4 Example Monomers* Initiator Terminator Mn Mw Mw/Mn 26 BA/MMA/BA2-H2PN Allyl OH 23,000 44,000 1.9 (1.8 mmol) (110 mmol) 27 BA/STY/BA2-H2PN Pentene OH 23,000 50,000 2.19 (1.8 mmol) (210 mmol) *STY isstyrene

A comparison between the melt viscosities and cohesive strengths ofconventional hot melt acrylic polymers and the new hot melt polymersdescribed in Table 6 is set forth below.

TABLE 6^(a) Relative Melt Relative Cohesive Example PolymerViscosity^(b) Bond Strength^(c) 30 Ref. 2 1 1 (Table 3) 31 26 3.2 2(Table 5) 32 27 2.8 3 (Table 5) ^(a)The data has been normalized to 1based on the reference sample. ^(b)The higher the relative meltviscosity ratio, the greater the ability of the polymer to melt andflow. ^(c)The higher the relative cohesive bond strength relativenumber, the greater the bond strength of the hot melt adhesives adheredto two pieces of aluminum metal.

Now, the only significant difference between polymer 26 and polymer 27is the alcohol used to terminate the structure. It is believed that thepentene alcohol may be a mixture of pentene alcohols where branchedspecies are present. It is believed that such branching is responsiblefor the different adhesive performances reported herein. Note, that thereported tack data in Table 3 also shows a marked difference in adhesiveperformance between those polymers terminated with allyl alcohol andthose terminated with pentene alcohol.

When end-capping the telechelic (co)polymer, is conceivable that theinefficiencies of such process may produce a mixture of hydroxyl-capped(co)polymer and initial telechelic (co)polymer. Such mixture may betermed a “self-assembled” adhesive because a balance of properties isachieved in situ by the synthesis steps (mixture of components) ratherthan by blending different components as is conventional in adhesiveformulation technology. Based on these results, it is believed that therelative tack value, Mn and Mw of the chain extended polymers, can bepredicted based on the Mn of the initial telechelic polymers synthesizedas disclosed herein.

What is claimed is:
 1. An adhesive (co)polymer, which comprises: apolyisocyanate chain extended poly-telechelic (co)polymer wherein saidpoly-telechelic (co)polymer has a narrow molecular weight distribution(Mw/Mn) and is made by polymerizing one or more radically-polymerizablemonomers in the presence of a transition metal, a ligand, and aninitiator, under atom or group transfer radical polymerizationconditions, wherein OH groups are contained on one or more of saidinitiator, an initiating monomer, a polymerizable monomer, a terminatingmonomer, or combinations thereof.
 2. The adhesive (co)polymer of claim1, wherein said transition metal is Cu⁺¹ or Co⁺¹.
 3. The adhesive(co)polymer of claim 2, wherein said Cu⁺¹ transition metal is suppliedfrom a Cu⁺¹ halide-bipyridine complex.
 4. The adhesive (co)polymer ofclaim 2, wherein said Co⁺¹ transition metal is supplied from anorganocobalt porphyrin complex.
 5. The adhesive (co)polymer of claim 1,wherein said ligand is selected from the group consisting of halides,bipyridyls, mercaptides, triflates, olefins, hydroxyl complexes, andcombinations thereof.
 6. The adhesive (co)polymer of claim 1, whereinsaid initiator is selected from the group consisting of 2-hydroxyethyl2-bromopropionate, 2-hydroxyethyl 4-bromopropionate, methyl2-bromopropionate, 1-phenyl ethyl chloride, 1-phenylethyl bromide,chloroform, carbon tetrachloride, 2-chloropropionitrile, C₁-C₆ esters of2-halo-C₁-C₆ carboxylic acids, α,α′-dichloroxylene, α,α′-dibromoxylene,hexakis(a-bromomethyl)benzene, and combinations thereof.
 7. The adhesive(co)polymer of claim 1, wherein said polyisocyanate is selected from thegroup consisting of hexamethylene diisocyanate, toluene diisocyanate(TDI), diphenylmethane diisocyanate (MDI), m- and p-phenylenediisocyanates, bitolylene diisocyanate, cyclohexane diisocyanate (CHDI),bis-(isocyanatomethyl) cyclohexane (H₆XDI), dicyclohexylmethanediisocyanate (H₁₂MDI), dimer acid diisocyanate (DDI), trimethylhexamethylene diisocyanate, lysine diisocyanate and its methyl ester,isophorone diisocyanate, methyl cyclohexane diisocyanate, 1,5-napthalenediisocyanate, xylylene and xylene diisocyanate and methyl derivativesthereof, polymethylene polyphenyl isocyanates,chlorophenylene-2,4-diisocyanate, and combinations thereof.
 8. Theadhesive (co)polymer of claim 1, wherein said radically-polymerizablemonomers are selected from the group consisting of allyl (meth)acrylate,C₁-C₂₂ alkyl and cycloalkyl (meth)acrylates, (meth)acrylated epoxyresins, (meth)acrylated silicone resins, (meth)acrylated polyurethaneresins, hydroxyl derivatives of the foregoing monomers, and combinationsthereof.
 9. The adhesive (co)polymer of claim 1, wherein said hydroxylgroups are contained on: (i) one or more of said initiator, aninitiating monomer, a polymerizable monomer, or combinations thereof;(ii) one or more of a polymerizable monomer, a terminating monomer, orcombinations thereof; or (iii) one or more of said initiator, aninitiating monomer, a terminating monomer, or combinations thereof.(iii) one or more of said initiator, an initiating monomer, aterminating monomer, or combinations thereof.
 10. The adhesive(co)polymer of claim 1, wherein a terminating hydroxyl monomer is usedfor form said poly-telechelic (co)polymer and the adhesive (co)polymercomprises a mixture of said poly-telechelic (co)polymer and saidchain-extended poly-telechelic (co)polymer.